Anti-abortion groups are planning to take advantage of the new Republican dominance in American politics to push through restrictions on abortions, prompting their opponents to claim that a woman's right to choose is now under greater threat than at any time for a century.

The new Senate majority leader, Bill Frist, is seen by the anti-abortion movement as a key figure. They believe his background as a surgeon will give him extra clout with wavering politicians.

"It may sound strange in 2003 to say that a woman's reproductive rights are now under threat, but that is a real possibility," Kate Michelman of the National Abortion and Reproductive Rights Action League (Naral) said yesterday.

She said that the anti-abortion movement's ultimate aim was to make all a crime. .

Douglas Johnson, legislative director of the National Right to Life Committee, said yesterday that more anti-abortion politicians had been elected to the Senate and the House of Representatives in November.

The Republicans control the White House, Senate and House of Representatives, and will do so until 2004.

Among the legislative changes sought is a ban on the so-called "partial birth" abortion, which involves partially delivering the foetus; the establishment of a right for hospitals to refuse to carry out abortions without running the risk of losing federal funding; and the creation of a new crime of taking a minor across state borders for an abortion.

Mr Johnson said the public opinion polls showed that support for a ban on partial abortion was overwhelming. But opponents say it is a rarely used procedure employed in late abortions to protect the health of the woman, and is being exploited by the anti-abortion lobby.

"Partial birth is not a medical term and it has been deliberately used in a very evocative way to inflame the debate and keep the focus away from the real issue," Ms Michelman said.

"They know they can only really count on two years [when all legislative bodies are under Republican control], so they are going to push very hard for every measure to restrict a woman's right to choose.

"Will they be successful? I hope not. But there is no longer any firewall against those who want to take away a woman's right to choose."

Another front on which the anti-abortion movement is active is the appointment of judges who interpret the law.

The battle in the Senate for approval of judges with strong views is likely to be intense.